Influence of nucleotide excision repair on N-hydroxy-2-acetylaminofluorene-induced mutagenesis studied in lambda lacZ-transgenic mice.
To study the influence of nucleotide excision repair (NER) on mutagenesis in vivo, ERCC1 +/-, XPA-/-, and wild-type (ERCC1+/+ and XPA+/+, respectively) lambda lacZ-transgenic mice were treated i.p. with N-hydroxy-2-acetylaminofluorene (N-OH-AAF) and lacZ mutant frequencies were determined in liver. No significant effect of the treatment on the mutant frequency in wild-type or ERCC1-heterozygous mice was observed. The liver mutant frequency appeared to be significantly increased in treated XPA-/- mice only. To distinguish N-OH-AAF-induced from spontaneous mutations, lacZ mutants derived from treated XPA-/- mice were subjected to DNA-sequence analysis and the spectrum obtained was compared to that established for lacZ mutants in liver of PBS-treated lambda lacZ-transgenic mice of the parent strain 40.6. The N-OH-AAF-induced mutation spectrum appeared to be significantly different from the spontaneous mutation spectrum: the former consisted of mainly (19/22) single bp substitutions targeted at G, of which the majority (12/19) were G:C-->T:A transversions, suggesting that N-(deoxyguanosin-8-yl)-2-aminofluorene [dG-C8-AF], the major DNA adduct in N-OH-AAF-treated mice, is the premutagenic lesion. After analysis of 21 spontaneous mutants, only ten single bp substitutions targeted at G were found, of which five were G:C-->T:A transversions. This study with XPA-/- lambda lacZ-transgenic mice shows that one of the components of NER, that is, the XPA protein, suppresses mutagenesis in vivo.
Frijhoff
A F
AF
Department of Molecular Toxicology, TNO Nutrition and Food Research Institute, Zeist, The Netherlands.
Krul
C A
CA
de Vries
A
A
Kelders
M C
MC
Weeda
G
G
van Steeg
H
H
Baan
R A
RA
D000818:Animals; D004260:DNA Repair; D004268:DNA-Binding Proteins; D004720:Endonucleases; D006881:Hydroxyacetylaminofluorene / Q000633:toxicity*; D007763:Lac Operon; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009153:Mutagens / Q000633:toxicity*; D011506:Proteins / Q000235:genetics
D004268:DNA-Binding Proteins; D009153:Mutagens; D011506:Proteins; D006881:Hydroxyacetylaminofluorene; D004720:Endonucleases; C499360:Ercc1 protein, mouse